1. Field of the Invention
The present invention relates to a method for manufacturing a wiring board and a method for manufacturing an inkjet printhead substrate.
2. Description of the Related Art
A wiring board having through-silicon vias is used for high-density silicon IC (integrated circuit) chip packages and various devices, such as electronic devices and optical devices.
The through-silicon via is an electrode formed by filling a through or non-through small pore (more specifically, a small pore in which an insulating layer is formed on the wall thereof) in a semiconductor substrate or a multilayer semiconductor substrate with a conductive material.
Japanese Patent Laid-Open No. 2006-032699 discloses a method for forming through-silicon vias by forming a seed layer in through via holes in a substrate by vacuum deposition and thereafter filling the through via holes with a conductor by an electrolytic plating method.
Japanese Patent Laid-Open Nos. 2004-095849 and 2003-257891 disclose a method for forming through-silicon vias by filling through via holes with conductive paste made of silver or copper by a stencil printing method or a vacuum differential pressure method and burning it.
However, with the method described in Japanese Patent Laid-Open No. 2006-032699, the use of a vacuum deposition unit increases the cost of the apparatus, resulting in an enormous initial investment for mass production. In forming the conductor in the via holes by the electrolytic plating method, in order to uniformly plate the interior of the via holes with the conductor without voids, the plating speed must be low until a sufficient amount of plating solution can be spattered. This makes it difficult to satisfy practical mass-production tact, resulting in high mass-production cost.
On the other hand, the methods described in Japanese Patent Laid-Open Nos. 2004-095849 and 2003-257891 have the problem of an increase in mass production cost due to an increase in the number of processes. The stencil printing method needs an alignment work of positioning a stencil printing plate on a semiconductor substrate, thus increasing the number of processes. The vacuum differential pressure method also needs masking and alignment works for applying conductive paste on desired positions, thus increasing the number of processes.